The 32-mg, single IV dose of ondansetron hydrochloride no longer will be marketed because of the potential for serious cardiac risks, according to the FDA. Ondansetron hydrochloride (Zofran, GlaxoSmithKline) has been used to prevent chemotherapy-induced nausea and vomiting. The FDA issued a drug safety communication in June urging clinicians to stop using the 32-mg, single IV dose due to the risk for QT interval prolongation. QT interval prolongation can lead to torsades de pointes, a potentially fatal heart rhythm. Those doses — which are sold pre-mixed in solutions of either sodium chloride or dextrose — will be removed from the market through the early part of 2013, according to an FDA press release.